Challenging P6 SA1 P2 NY Q15

15. The series of figures below are made of cubes. Study the diagram below and answer the following questions.

a) How many cubes are there in Figure 6? [2]

b) Which figure will have 120 cubes? [2]

1

1 + 3 = 4                                            1 + 2 = 3

1 + 3 + 6 = 10                                    1 + 2 + 3 = 6

1 + 3 + 6 + 10 = 20                            1 + 2 + 3 + 4 = 10

1 + 3 + 6 + 10 + 15 = 35                    1 + 2 + 3 + 4 + 5 = 15

1 + 3 + 6 + 10 + 15 + 21 = 56            1 + 2 + 3 + 4 + 5 + 6 = 21

a) There are 56 cubes in Figure 6.

56 + 28 = 84                                    21 + 7 = 28

84 + 36 = 120 --> Figure 8                28 + 8 = 36

b) Figure 8 will have 120 cubes.