Multiple choice

If a number is divided by $45$, then the remainder is $32$. If the same number is divided by $15$, then the remainder is

  1. $2$
  2. $3$
  3. $16$
  4. $4$
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A Correct answer
Explanation

If a number N = 45k + 32, we want to find the remainder when N is divided by 15. N = 15(3k) + 30 + 2 = 15(3k + 2) + 2. The remainder is 2.

AI explanation

Apply the congruence modulo property that if a number leaves a remainder of 32 when divided by 45, it can be expressed as 45k plus 32. Because 15 is a factor of 45, the term 45k is perfectly divisible by 15. Divide the remaining remainder 32 by 15, which gives a new quotient of 2 and a leftover remainder of 2. The final remainder is 2.