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-digit numbers the sum of all digits is 7?
The Absolute Best Book to Challenge Your Smart Student!

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.
The Absolute Best Books to Ace Algebra
Related to This Article
More math articles
- Top 10 3rd Grade NYSE Math Practice Questions
- 4th Grade SOL Math Worksheets: FREE & Printable
- The Best CBEST Math Worksheets: FREE & Printable
- Is the CBEST Math Difficult?
- How to Study Math Effectively in College?
- 5th Grade AZMerit Math Worksheets: FREE & Printable
- Top Calculators for the PSAT 8/9 Math Test
- Top 10 7th Grade NYSE Math Practice Questions
- Decoding Data: How to Identify Representative, Random, and Biased Samples
- Area and Perimeter
What people say about "Geometry Puzzle – Critical Thinking 20 - Effortless Math: We Help Students Learn to LOVE Mathematics"?
No one replied yet.