What is the sum of all the whole numbers from 1 to 10 inclusive?
55
Using Gauss's formula n(n+1)/2, for n=10, 10(11)/2 = 55.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Easy. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
More math riddles
A father and son calculate that their current ages add up to 66. The father notes that his age is the exact reverse of his son's age (the same two digits in opposite order). Assuming the father is strictly older than the son, how many different valid age pairs could they be?
Eli has 8 shells. Lily has twice as many. How many shells do they have together?
When you multiply me by 2, the product is 15 less than the value of my square. If I am a positive integer, what number am I?
When you multiply me by any positive integer, the sum of the digits of the resulting product—when repeatedly summed until one digit remains—is always me. What single-digit number am I?
Omar has 6 icicles. Ava has twice as many. How many icicles do they have together?
15 leprechauns are shared equally among 3 friends. How many leprechauns does each friend get?