Question:
Tick (✓) the correct answer
If 4xy7 is exactly divisible by 3, then the least value of (x + y) is
(a) 1
(b) 4
(c) 5
(d) 7
Solution:
(a) 1
If a number is divisible by 3, the sum of the digits is also divisible by 3.
$4+x+y+7=11+(x+y)$
For the sum to be divisible by 3 :
$11+(x+y)=12 \Rightarrow(x+y)=1$
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