question_answer

Fatima wants to mail three parcels to three village schools. She finds that the postal charges are Rs. 20, Rs. 28 and Rs. 36, respectively. If she wants to buy stamps only of one denomination, what is the greatest denomination of stamps she must buy to mail the three parcels?

Answer:

The greatest denomination of stamps she must buy to mail the three parcels is the HCF of 20, 28 and 36. Prime factorization of 20, 28 and 36.

2	20
2	10
5	5
1

2	28
2	14
7	7
1

2	36
2	18
3	9
3	3
1

\[20=2\times 2\times 5\] \[28=2\times 2\times 7\] \[36=2\times 2\times 3\times 3\] \[\therefore \] HCF \[=2\times 2=4\]