I thought of a two-digit number. The unit digit of my number is a prime number, and the tens digit is four times as big as the unit digit. What is my number?

Question

Mathematics

Elyse Durham

29 March, 14:41

I thought of a two-digit number. The unit digit of my number is a prime number, and the tens digit is four times as big as the unit digit. What is my number?

+3

Answers (1)

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Terrance Weber · Answer 1

let the number is 10x + 3.

then sum of its digits = x + 3.

from given condition, we have

x+3 = (1/7) * (10x + 3)

=> 7x + 21 = 10x + 3

=> 3x = 18

=> x = 6

therefore the number is 63.