Regd. Office Answers & Solutions - Aakash

1. How many positive integers less than 1000 have the property that the sum of the digits of each such number is divisible by 7 and the number itself is divisible by 3? Answer (28) Sol. Sum of the digits is divisible by 7 and number itself is divisible by 3 ∴ x + y + z = 21, x, y, z are digits 0, 1, 2, ...., 9. ∴ Coefficient x21 is (x0 + x1 ... ................
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