For a parent. These are the answers (4 A4 sheets). They are in nothing the child is given.

Answer key (for a parent)Week 03 · younger son1 / 4

Answers and reasoning

Question 1 is handed over already worked

Tue 15 Sept — big numbers

(printed) 86 | 000 | 000 → 86,000,000

240,000,000

50 | 700 | 000 → 50.7 million

3 billion (3,000,000,000)

90 billion

1.2 billion > 500 million > 80 million. 10 digits, 9 digits, 8 digits.

750,000,000

1,200,000,000,000

400 million

310 million > 300 million > 290 million

100 times — two more zeros

60 million + 50 million = 110 million

150 million ÷ 10 million = 15 times

extra 1

A trillion is 10,000 times a hundred million (four places apart)

extra 2

120 − 98 = 22 million

Answer key (for a parent)Week 03 · younger son2 / 4

Answers and reasoning

Wed 16 Sept — costume 1

1-1

28 ÷ 5 = 5 teams, 3 left over

1-2

34 ÷ 6 = 5 teams, 4 left over

1-3

No fixed answer. 'They sit out', 'they join existing teams', 'they make another team' are all fine — accept it if a reason is given.

1-4

5 x 8 = 40 people

1-5

48 ÷ 5 = 9 per team, 3 left over

1-6

12 x 3 = 36 — the same person is counted more than once

2-1

6000 ÷ 1000 = 6 MB

2-2

64 ÷ 2 = 32 photos

2-3

1000 ÷ 450 = 2 remainder 100 → 2 videos, 100 MB left

2-4

1000 x 3 = 3000 MB

2-5

250 x 4 = 1000 MB = 1 GB → it fits exactly

2-6

8000 ÷ 4 = 2000 photos

Fri 18 Sept — long division

(printed) 96 ÷ 4 = 24

252 ÷ 6 = 42

365 ÷ 7 = 52 remainder 1

Answer key (for a parent)Week 03 · younger son3 / 4

Answers and reasoning

816 ÷ 8 = 102. In the tens, 1 ÷ 8 = 0 remainder 1, so write the zero. Leaving it out gives 12.

423 ÷ 9 = 47 (47 x 9 = 423 ✓)

130 ÷ 8 = 16 remainder 2 → 16 each, 2 left over

504 ÷ 8 = 63

731 ÷ 5 = 146 remainder 1 (5 x 146 + 1 = 731 ✓)

900 ÷ 7 = 128 remainder 4 (7 x 128 + 4 = 900 ✓)

37 x 8 = 296

6 x 23 + 4 = 142. Forgetting to add the remainder, and answering 138, is the common slip here.

142 ÷ 6 = 23 remainder 4 — back where we started, so it is right

200 ÷ 9 = 22 bags, 2 left over

extra 1

7 x 52 + 1 = 365

extra 2

45 x 6 = 270

Answer key (for a parent)Week 03 · younger son4 / 4

Answers and reasoning

Sun 20 Sept — costume 2, corrections, trees

1-1

92 ÷ 8 = 11 remainder 4 → 11 each, 4 left over

1-2

4 ÷ 8 = ¹⁄₂ → half a biscuit each. This is where fractions come from, and it leads straight into the Grade 5 topic 'fractions and division'.

1-3

96 ÷ 8 = 12 boxes

2-1

96,000 ÷ 4 = 24,000

2-2

96,000 ÷ 8 = 12,000. Twice as many sharing, half as much each.

2-3

1200 ÷ 5 = 240 points

20 ÷ 5 = 4 gaps. One more flag than gaps → 5 flags.

Both ends get a flag, so add 1. Drawing it makes it obvious.

24 ÷ 4 = 6 gaps → 7 flags

9 flags means 8 gaps. 8 x 3 = 24 m

60 ÷ 5 = 12 stickers. Going all the way round there are no ends, so there is no +1.

A straight road has two ends, so there is one more flag than gap. A round table has no ends, so stickers and gaps come out equal.

Saying whether there are ends is enough. His brother has the same question on Sunday, in trees and a pond.