# Geometry Puzzle – Critical Thinking 20

To solve this kind of challenge, sometimes it just needs logical steps and other times it involves lateral out-of-the-box thinking!

## Challenge:

In how many 3 digits number the sum of all digits is 7?

$11.99 Satisfied 123 Students The correct answer is 28. First, let’s find all three digits that add up to 7. 700, 610, 511, 520, 430, 421, 322, 133 For 7, 0 and 0, we can write only one three digit number which is 700. For 6, 1 and 0, we can find 106, 160, 601, 610, For 5, 1, and 1: 115, 151, 511 For 5, 2, and 0: 205, 250, 502, 520 For 4, 3, and 0: 304, 340, 403, 430 For 4, 2, and 1: 124, 142, 214, 241, 412, 421 For 3, 2, and 2: 223, 232, 322 For 1, 3, and 3: 133, 313, 331 There are 28 three digits numbers that the sum of their digits is 7. ### More math articles ### What people say about "Geometry Puzzle - Critical Thinking 20"? No one replied yet. X 30% OFF Limited time only! Save Over 30% SAVE$5

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