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Shelf brackets — a carpenter buys webbing tape
A carpenter is making straps for 140 shelf brackets. Each strap needs 65 cm of webbing tape. The tape is sold in rolls of 15 m. How many rolls must the carpenter buy?
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The carpenter must buy 7 rolls. One roll gives 23 complete straps, so 6 rolls give only 138 straps, while 7…
The pattern behind it: Number × value
One batch repeats. Work out one batch, then multiply.
In this one. Round down when counting complete straps within one roll, then round up when counting whole rolls to buy.
How to spot it
Items are described as a fixed group or ratio that repeats, such as tiles following a pattern, snacks sold in a fixed mix, or a rate given per hour or per item.
Common mistake
Children start from the grand total instead of first working out what one batch is worth. In rate questions they also confuse a duration with a clock time.
Try one like it
Standard Flags for a parade — reels of string A scout troop is preparing 320 flags for a parade. Each flag needs 45 cm of string to tie it to a pole. String is sold in reels of…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.