Running head: RAPID MATH TRICKS AND TIPS1Rapid Math Tricks and Tips: Trick 30 and 37Ashleigh RussellConcordia University

RAPID MATH TRICKS AND TIPS2Rapid Math Tricks and Tips: Trick 30 and 37Algorithm Summary-Trick 30: Rapidly Subtract by Adding-A VariationThis technique teaches students to subtract by adding. When the minuend and subtrahend of a subtraction problem are on opposite sides of 100, 200 etc., determine the distance the number is from that multiple of 100 and add those numbers together to obtain the answer (Julius,1992). In other words, instead of subtracting, you determine the distance the two numbers are from a multiple of 100 and those two numbers together. For example, 143-98, 143 is 43 above 100 and 93 is 3 below 100, 43+2= 45. Another example, 245-189, 245 is 45 above 200 and 189 is 11 below 200, 45+11= 56.This algorithm was not difficult to learn and is an easy technique to learn. At first glance,I thought how in the world do you subtract by adding but after reviewing the examples and completing the practice problems, it came easy. This algorithm requires prior knowledge of estimating and rounding. They need to be able to determine which multiple of 100 they will be using and how to determine the distance between numbers. I enjoyed learning this algorithm