1 In the model shown, each block is divided into tenths. Each completely shaded block represents 1 whole and there are two partially shaded blocks. One block shows 5 tenths shaded, and the other block shows 7 tenths shaded.
2 To subtract, regroup one of the completely shaded blocks into tenths.
3 Now, subtract 7 tenths from 15 tenths.
4 15 tenths - 7 tenths = 8 tenths and the wholes too get canceled. So, 2.5 - 1.7 = 0.8. [Subtract.]
