4.2 4.2 Arithmetic with negative numbers ● ●
I can carry out additions and subtractions involving negative numbers I can use a number line to calculate with negative numbers
Develop fluency Worked example Use a number line to work out the answers. a 5 – 13 b (–11) + 9 c 6 – 12 – 3 a Starting at zero and ‘jumping’ along the number line to 5 and then back 13 gives an answer of –8. –13
t n e t n its o c d e e l o p t t m c Sa bje u S +5
–8
0
5
b Similarly, (–11) + 9 = –2 Notice that brackets are sometimes used so that the negative sign is not confused with a subtraction sign. +9
–11
–11
–2
0
c Using two steps this time, 6 –12 – 3 = –9 –3
–12
+6
–9
–6
0
6
1 Use a number line to work out the answers. a 1–5 b 4–6 c 2–3
d 1–9
2 Use a number line to work out the answers. a –2 + –4 b –5 + –2 c –3 + –1
d –8 + –7
3 Use a number line to work out the answers. a –1 + 3 b –4 + 3 c –2 + 2
d –2 + 6
4 Use a number line to work out the answers. a –3 – 1 b –3 – 3 c –1 – 4
d –3 – 8
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