Question

Find the smallest number which when divided by 28 and 32 leaves remainders 8 and 12 respectively.

Answer 1

Let the required number be x.

Using Euclid's lemma,
x = 28p + 8 and x = 32q + 12, where p and q are the quotients
⇒ 28p + 8 = 32q + 12
⇒ 28p = 32q + 4
⇒ 7p = 8q + 1 ..... (1)

Here p = 8n − 1 and q = 7n − 1 satisfies (1), where n is a natural number
On putting n = 1, we get
p = 8 − 1 = 7 and q = 7 − 1 = 6

Thus, x = 28p + 8
= 28 × 7 + 8
= 204

Hence, the smallest number which when divided by 28 and 32 leaves remainders 8 and 12 is 204.