Answer key · Set C
A Shape With More Pieces
128 The left piece is 4 wide and 7 tall: 4 × 7 = 28.
215 The right piece is 5 wide and 3 tall: 5 × 3 = 15.
3True Any way you cut the shape, the pieces add to the same area. 27 + 16 = 43, and 28 + 15 = 43.
420 Half of 8 × 5 = 40 is 20.
58 × 4 + ½ × 8 × 3 The rectangle is 8 × 4. The roof is half of 8 × 3. Add them. 8 × 7 would make the roof a full rectangle.
644 The rectangle is 8 × 4 = 32. The roof is half of 8 × 3 = 24, which is 12. 32 + 12 = 44.
730 The rectangle is 6 × 4 = 24. The triangle has a base of 3 and a height of 4, so its area is half of 12, which is 6. 24 + 6 = 30.
8False The whole rectangle is 6 × 5 = 30. The two triangles share it equally, so each is 15.
936 The pieces are 3 × 6 = 18, 3 × 4 = 12 and 3 × 2 = 6. 18 + 12 + 6 = 36.
101-D, 2-A, 3-B, 4-C Find each piece (a triangle is half of base times height), then add.
1128 + 15, 27 + 16, 63 − 20 28 + 15 and 27 + 16 add the pieces of two different cuts. 63 − 20 takes the missing corner away from the 9 by 7 box. 9 × 7 is the whole box, and 4 × 7 + 9 × 3 counts the corner piece twice.
123, 2, 4, 1 Cut the shape, find each piece, then add.
13Your own words: a grown-up reads it.
Mark each answer, count the right ones and write the score on the sheet.