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!
[include_netrun_products_block from-products="product/ged-math-test-prep-in-30-days-complete-study-guide-and-test-tutor-for-ged-mathematics-the-ultimate-book-for-beginners-and-pros-two-practice-tests/" product-list-class="bundle-products float-left" product-item-class="float-left" product-item-image-container-class="p-0 float-left" product-item-image-container-size="col-2" product-item-image-container-custom-style="" product-item-container-size="" product-item-add-to-cart-class="btn-accent btn-purchase-ajax" product-item-button-custom-url="{url}/?ajax-add-to-cart={id}" product-item-button-custom-url-if-not-salable="{productUrl} product-item-container-class="" product-item-element-order="image,title,purchase,price" product-item-title-size="" product-item-title-wrapper-size="col-10" product-item-title-tag="h3" product-item-title-class="mt-0" product-item-title-wrapper-class="float-left pr-0" product-item-price-size="" product-item-purchase-size="" product-item-purchase-wrapper-size="" product-item-price-wrapper-class="pr-0 float-left" product-item-price-wrapper-size="col-10" product-item-read-more-text="" product-item-add-to-cart-text="" product-item-add-to-cart-custom-attribute="title='Purchase this book with single click'" product-item-thumbnail-size="290-380" show-details="false" show-excerpt="false" paginate="false" lazy-load="true"]
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
- What if I Fail the CBEST Test?
- SSAT Upper-Level Math Worksheets: FREE & Printable
- 5 Best Digital Pen Tablets for Online Math Teaching in 2026
- Grade 6 Math: Adding Fractions with Unlike Denominators
- 3rd Grade PSSA Math Practice Test Questions
- Top 10 PERT Math Prep Books (Our 2023 Favorite Picks)
- Intelligent Math Puzzle – Challenge 86
- How to Find Similar and Congruent Figures?
- What Are the Applications of Inverse Trigonometric Functions?
- How to Graph Absolute Value Inequalities?

















What people say about "Geometry Puzzle – Critical Thinking 20 - Effortless Math: We Help Students Learn to LOVE Mathematics"?
No one replied yet.