Mental calculation technique Example Mental calculation Reason 398*4 1600-8=1592 398*4=(400-2)*4 =400*4-2*4 =1600-8 240*5 120*10 divide by 2 and multiply by 10 240*5=240*10/2 =(240/2)*10 =120*10 320/5 640/10 multiply by 2 and divide by .. read more.
Quick Table of Multiples [Multiple of 2] If the last figure of a number is even, then the number is a multiple of 2. [Multiple of 3] If the sum of every .. read more.
Question: Sam put 18 pencils in 3 equal groups. How many pencils are in each group? Strategy: 1) UNDERSTAND: What do you need to know? You need to know that there are .. read more.
Question: Amy and Judy sold 12 show tickets altogether. Amy sold 2 more tickets than Judy. How many tickets did each girl sell? Strategy: 1) UNDERSTAND: What do you need to find? .. read more.