Home Learning Maths Subtraction Strategies

Last week Room 19 were using different strategies to work out subtraction problems. Here are two of my strategies.

 James brought 15.54 metres  of material. He needed 13.16 metres to make a t-shirt for Hagrid. How much material would be left over after James had finished making the t-shirt? Have a go at using these two effective strategies.

     Reversibility
   15.54 -13.16 = ?
   13.16 + 2.38 = 15.54
   13.16 + 0.04 ➝ 13.20
   13.20 + 0.80 ➝ 14.0
   14.0 + 1.0 ➝ 15.0
   15.0 + 0.50 ➝ 15.50
   15.50 + 0.04 = 15.54
   James had 2.38 metres left

   Equal adjustments
   15.54 - 13.16 = 2.38m
   +0.46   +0.46
   16.0 - 13.62 = 2.38m
   James had 2.38 metres left