Adding up building blocks

A child s set of building blocks usually consists of many wooden cubes — all the same size and decorated with letters of the alphabet, numbers, animals, or different colors. A typical stacking exercise involves making a row of blocks, with each block touching the one next to it, and then making a row on 

The Problem Little Jimmy is stacking his cube-shaped blocks. His first row has 20 blocks, and each subsequent row has one block less than the one below. If there are 250 blocks in Jimmy s set, will he have enough blocks to build a structure all the way up to one block on the top  

Find the sum of the consecutive integers 1, 2, 3, 4, 5. 19, 20 by using the formula for the sum of consecutive integers. The first term is 1 the last term is 20 and the number of terms, n, is 20. Compare that sum with the number of blocks to see if Jimmy will have enough blocks. 

Jimmy has more than enough blocks. In fact, he ll probably throw those extra blocks at his brother. 

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