Mei Ling and Priya had 870 stickers altogether. Mei Ling had more stickers than Priya. After Priya bought another 150 stickers, Mei Ling had 90 more stickers than Priya.
- How many more stickers than Priya did Mei Ling have at first?
- How many stickers did Mei Ling have at first?
Need a hint?
Draw two bars for Mei Ling and Priya at first. Priya's bar is shorter. How much shorter was it before she bought the 150 stickers?
Worked answer
- (a) After Priya bought 150 stickers, Mei Ling still had 90 more than her.
- So before buying, Priya was further behind: 90 + 150 = 240 stickers. Mei Ling had 240 more stickers than Priya at first.
- (b) Take the difference away from the total: 870 − 240 = 630. This is Priya's stickers twice.
- Priya at first: 630 ÷ 2 = 315 stickers.
- Mei Ling at first: 315 + 240 = 555. Check: 555 + 315 = 870, and 555 − 315 = 240.
- Mei Ling had 555 stickers at first.
The mistake this question tests
Calculation slip
Many pupils use 90 as the difference at first, but 90 is the difference after Priya bought 150 more stickers. At first the gap was 90 + 150 = 240.
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See the answer →Practise PSLE whole numbers until the mistakes stop.
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