Current Affairs 2nd Class

  Numbers   Number System:     
  • The number system contains ten digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
  • The smallest 1 - digit counting number is 1.
  The largest and the smallest numbers:  
  • The smallest 1 - digit number is 0 and the largest 1 - digit number is 9.
  • The smallest 2 - digit number is 10 and the largest 2 - digit number is 99.
  • The smallest 3 - digit number is 100 and the largest 3 - digit number is 999.
Place Value Chart:     
Thousands Hundreds Tens Ones
1000 100 10 1
 
  • 10 Ones =1 Ten
  • 10 Tens = 1 Hundred
  • 10 Hundreds = 1 Thousand
  Place Value of each digit in a number: In a three digit number, there are three places, namely - Ones place, Tens place and Hundreds place.                Ascending Order of numbers: Arranging numbers from the least number to the largest number is called Ascending Order. e.g., 13, 67,132,168 are numbers in ascending order. Descending Order of numbers: Arranging numbers from the largest number to the least number is called Descending Order. e.g., 168,132, 67, 13 are numbers in descending order.
Symbol Meaning Example
= (is equal to) The numbers on both the sides of = symbol have the same value. 25 = 25
< (is lesser than) The number on the closed side of < symbol is lesser than the number on its open side. 23 < 25  
> (is greater than) The number on the open side of > symbol is greater than the number on its closed side.    28 > 25
Rules for comparison of numbers: Rule 1:           A numeral containing more digits is greater.   Rule 2:           If two numerals contain the same number of digits, the numeral having greater digit at the left most place will be greater.   Rule 3:           If the left more...

  Addition and Subtraction                                        Synopsis ADDITION:    
  • Taking things (or numbers) together is called addition. + is the symbol for addition.
 
e.g.,           5            +           3             =          8                   \[\downarrow \]                       \[\downarrow \]                       \[\downarrow \]                Addend             Addend                Sum
 
  • When 0 is added to a number, the sum is the same number. e.g., 6 + 0 = 6
  • When 1 is added to a number, the sum is the next number. g., 4 + 1 = 5
 
Note:-     Adding two numbers in any order        gives the same sum. e.g.,             3 + 5 = 8 and 5 + 3 = 8  
 
  • Regrouping: Writing a number in different ways is called regrouping.
e.g.,          16 ones = 1 ten 6 ones 25 tens = 2 hundreds 5 tens
  • Addition of two number with carry:
When two numbers in ones place are added, the sum may be greater than 9.    Then regroup the sum as tens and ones.                                   e.g., Add 276 and 389.                                                              6 + 9 = 15        15 = 1 ten 5 ones   Write the ones under the ones place and carry the number in tens to the tens place.             Then add the numbers in tens place along with the carry. Write the sum under tens place if it is less than or equal to 9.         If the sum of tens is greater than 9, again regroup the tens as hundreds and tens. 16 tens = 1 hundred 6 tens.   Write the tens in tens place and carry the hundreds to hundreds place. Add the numbers in hundreds place along with the carry and write the sum.             So, 276 + 389 = 665.                                                  Subtraction:
  • Taking away some things (or numbers) to find how much is remaining is called subtraction. - is the symbol for subtraction.
 
  • When 0 is subtracted from a number, the difference is the same number.
e.g., 6 - 0 = 6  

  Multiplication   Synopsis Multiplication:  
  • Multiplication is the same as repeated addition, x is the symbol for multiplication.
  • The number to be multiplied is called the MULTIPLICAND.
  • The number by which we multiply is called the MULTIPLIER.
  • The answer is called the PRODUCT.
e.g.,           24       \[\times \]            3               =           72                    \[\downarrow \]                     \[\downarrow \]                           \[\downarrow \]             Multiplicand       Multiplier         Product
       
Note:       The product of a number and zero is                                   zero.                    The product of a number and 1 is the                    number itself.                  Even if the order of the number to                              be multiplied is changed, the                        product remains the same.
  • Multiplication of a 1 - digit number by another 1 - digit number:
  • e.g.,    3 \[\times \] 9 = 27   Multiply the numbers and write the product.
  • Multiplication of a 2 - digit number by 1 - digit number:
  • e.g., 1: Multiply 98 by 3. First multiply ones and then multiply tens. Regroup the product if needed. Step -1: Multiply 8 ones by 3.                                            ® 8 ones \[\times \] 3 = 24 ones = 2 tens + 4 ones                               Write 4 in the ones place,                                                  Carry 2 tens to the tens place.                                                 Step-2: Multiply 9 tens by 3.                                       9 tens \[\times \] 3 = 27 tens                                           = 20 tens + 7 tens                                       = 2 hundreds + 7 tens                                                                Add the carried 2 tens to 7 tens. So, 7 tens + 2 tens = 9 tens. Write 9 in the tens place. Write 2 in hundreds place.
  • Multiplication of a 2 - digit number by another 2-digit number:
  • e.g., Multiply 36 by 25. Step - 1: First multiply ones.   Write 0 in the ones place and carry 3 tens to the tens place. Step - 2: Multiply the digit in tens place of the multiplicand by the ones digit of the multiplier. 3 \[\times \] 5 = 15. Now add the 3 carried from the product of ones to 15, which gives 15 + 3 = 18. Write 18 beside 0 in the product. Step - 3: Now place a 0 below 0 in the product 180. Multiply the digit 6 in ones place of the multiplicand by the digit 2 in tens place of multiplier.      6 \[\times \] 2 = 12 Write 2 below 8 in the more...

      Division   Synopsis   Division:  
    • Division is the reverse process of multiplication. It means grouping or sharing. It is also called repeated subtraction. - is the symbol for division.
    • Equal sharing or grouping means to divide the things equally without anything being left over or remaining.
    • The number which is divided is called the dividend. The number which divides the dividend is called the The number of times the divisor divides the dividend is called the quotient. The number of the dividend left undivided is called the remainder.
    e.g.,    In 20 \[\div \] 5 = 4, 20 is the dividend, 5 is the divisor and 4 is quotient when 20 is divided exactly by 5. So, remainder is 0.
    • 35 \[\div \] 3 can be written as \[\frac{35}{3}\].
    • Dividing 0 by a number gives 0. g., \[\frac{0}{5}=0\]
    • A number cannot be divided by 0. g., \[\frac{3}{0}\to \]cannot be done.
    • Dividing a number by 1 gives the same number as quotient, g., \[\frac{7}{1}=7\]
    • Dividing a number by itself gives 1 as quotient, g., \[\frac{6}{6}=1\]
    • Division of a 1 - digit number by another 1 - digit number, e.g., 9 \[\div \] 3 = 3.
    • Division of a 2 -digit number by a 1 - digit number, e.g., Divide 67 by 4.
    Note : Unlike addition, subtraction and multiplication which are done from the right most digit (i.e., ones) division is done from the left most digit of the dividend. 
    Step-1: 67 \[\div \] 4 Write the given division as shown.   Divisor \[\leftarrow \]  Step - 2:  Starting from the left most digit, find the number of times the divisor is in the digit. There is one 4 in 6. Put this 1 in quotient and 4 below 6 as shown. Quotient Step - 3: Now, subtract 4 from 6 in the dividend and write the difference 2 below the   Separator line Step - 4: Bring down the next digit (ie., 7) beside 2 as shown.    Find the number of 4's in the new dividend 27. 4 \[\times \] 6 = 24 and 4 \[\times \]7 = 28 So, there are 6 fours in the dividend 27. Write 6 beside 1 in the quotient and 24 below 27 as shown. Subtract 24 from 27 and write the difference 3 below the separator line shown.   more...

      Fractions   Synopsis   
    • A fraction is a part of a whole.  
    This is one whole. One whole circle is shaded.         The circle is divided into 2 equal parts. 1 out of the 2 equal parts is shaded. That means \[\frac{1}{2}\] of the circle is shaded. We say one half of the circle is shaded. Two - halves is a whole.          The circle is divided into 4 equal parts. Each equal part is called a quarter. 1 out of the 4 equal parts is shaded. That means - of the circle is shaded. We say one quarter of the circle is shaded. Four - quarters is a whole.   
    Note:    (1) One whole \[=1=\frac{2}{2}=\frac{3}{5}=\frac{4}{4}.........\]               (2) Two quarters is a half.  
         

      Length, Mass and Capacity   Synopsis     LENGTH
            The eraser is 3 cm long.                                The pencil is between 1 cm                                   and 10 cm.                                The pencil’s length is 10 cm                                - 1 cm = 9 cm.  
      The lengths of objects can be measured using a ruler or a tape. The lengths and heights of objects and distances between objects can be measured in centimetres (cm) and metres (m). Longer distances are measured in kilometres. 1 m = 100cm 1000 m = 1 km MASS (WEIGHT) The milk bottle is heavier than the 1 kg mass. The flour packet is as heavy as the 1 kg mass.   The bread is lighter than the 1 kg mass.          
    ·         Mass can be measured in kilograms (kg) and grams (g). ·         1 kg is equal to 1000 g. 1 kg is more than 1 g. ·         Half a kg is 500 g.    
      The mass of an object is measured using a scale. There are different types of scales. Each marking on the scale stands for different masses.   CAPACITY    Volume is the amount of liquid (e.g., water Juice) in a container. Capacity of a container is the volume of the liquid that it can hold. Volume is measured in litres (Z) and millilitres (m\[l\]). 1 I = 1000 m\[l\].              

      Shapes (2D and 3D)   Synopsis  
    Do you remember these shapes?    
      Formation of figures (2 - Dimensional):            
    This figure is made up of only straight lines. It has 5 straight lines.   This figure is made up of only curved lines. It has 8 curved lines. This figure is made up of straight lines and curved lines. It has 3 straight lines and 3 curved liens.
      Formation of figures (3 - Dimensional):        
    This parcel is made up of only flat surfaces. It has 6 flat surfaces. Some of them are hidden behind from our view. The ball is made up of only curved surfaces. It has 1 curved surface. The tin with lid is made up of flat surfaces and curved surface. It has 2 flat surfaces and 1 curved surface.
    more...

      Time   Synopsis    
    • Time is measured using a clock. The dial of a clock is divided into 12 equal divisions marked as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.
         
    • A clock has two hands:
    (i) long hand and (ii) short hand The long hand is called minute hand and the short hand is called hour hand. Between two immediate numbers on the clock, the minute hand reads 5 minutes and the hour hand reads 1 hour.
    • Some clocks have a third hand called second hand. It moves much faster than the other two hands.
    • The hour hand takes 12 hours to complete one round on the dial of the clock.
    • The minute hand takes 1 hour to complete one round on the dial of the clock.
    • 1 hour = 60 minutes; 1 minute = 60 seconds.
    So, 1 hour = 60 \[\times \] 60 = 3600 seconds.
    • In short, minutes is written as min, hours as h and seconds as s.
    • 1 day = 24 hours; 1 week = 7 days; 1 month = 4 weeks; 1 year = 12 months 1 year = 52 weeks; 1 year = 365 days
    • The time from 12 midnight to 12 noon is read as a.m. (Anti Meridian) and the time from 12 noon to 12 midnight as p.m. (Post Meridian).
    • A leap year has 366 days. In a leap year February has 29 days.
    • The years 2000, 2004, 2008, 2012, 2016, 2020 etc. are leap years. A leap year come once in every 4 years.
    • 30 days have September, April, June and November. All the rest have 31 days except February which has 28 days.
    • The time (in minutes) that pass after an hour is read as minutes past hour.
        2: 30 is read as 30 minutes past 2 or half-past 2.  
    • The length of the time (in minutes or hours) between two given times is called time duration.
    e.g., The duration between 11: 45 a.m. and 12:15 p.m. is 30 minutes.

      Money   Synopsis   
    • In India, the unit of money is RUPEE.
     
    • 100 paise make 1 Rupee. 50 paise make half a rupee.
     
    • Symbol for Rupee is Rs. Symbol for paise is p.
     
    • Rupees and paise are separated by a dot.
     
    • The figures on the left of the dot (.) denote Rupees, and the figures on the right of the dot (.) denote paise.
     
    • To convert rupees to paise, multiply by 100. g., Rs. 11.50 = 11.50 \[\times \] 100 = 1150 p
     
    • To convert paise to rupees, divide by 100,
     
    • g,, 1250 p = 1250 \[\div \,\] 100 = Rs. 12.50
    e.g., 50 p = Rs.  0.50    

      Pictographs   Synopsis    Pictograph:      
    • Numerical data when presented through pictures is called pictorial representation.
     
    • Pictorial representation of data is a useful method to represent data attractively.
     
    • A pictograph uses pictures or symbols to represent data.
     
    • It is very easy to understand data through pictures.
     
    • Pictographs are also called as pictograms.
       


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