![]() ![]() ![]() Teaching maths shortcuts will come back to bite you further down the line. In this case, there’s only one number to the left and this will confuse some children who can easily forget which direction to move. If we say that ‘you move the decimal point two places to the left’, we have a problem. Think of the decimal point like a concrete post - it exists to separate whole number places from decimal fraction places. They need to remember that the decimal point never moves (it’s another piece of faulty maths advice is to say that it does). I’ve seen learners come up with 00.05.įrom the outset, pupils need to grasp the idea that when you multiply by 10, 100, 1000 and so on, each digit shifts to the left on a place value table because they’re adding another place to the number. ![]() Pupils who have learned this rule might answer 0.050, or they could decide to add the zero somewhere else because they are unfamiliar with decimals. Imagine ‘adding a zero’ when multiplying 0.05 by 10. It’s possible that you’ll get 100 and 10.00 as responses.Īlthough taught as a helpful rule when multiplying by 10, ‘adding a zero’ is a maths misconception that stops learners from developing a deeper understanding of the base-ten system. Try this one with your class: 10 x 10 = 10.0 x 10 = In this example, 9.5 x 10 isn’t 9.50 because simply inserting a zero on the end gives exactly the same value. The ‘adding zeros’ trick can work when multiplying whole numbers by powers of 10, for example, 678 x 10 = 6780, 213 x 100 = 21300, 34 x 1000 = 34000, but this method completely falls down and is totally unsuitable when multiplying a decimal value by a power of 10. It’s almost taught like a sort of recipe but ‘adding a zero’ is like cooking the books, it’s maths fraud!īlindly accepting this method for multiplying by 10 means pupils apply this rule incorrectly because they don’t appreciate the underlying mathematics at work. This approach is limited in its usefulness and can be damaging. Maths learners often hear this misconception: “when multiplying by 10 just add a zero”. Should you just add a zero when multiplying by 10? I know teachers don’t deliberately set out to teach this misconception but many have inherited it from when they were in school innocently repeating it in their own practice. One all too common maths misconception is adding zeros when multiplying by a power of 10. Avoid this common maths misconception with our advice. If you’ve ever said ‘just add a zero’ when teaching how to multiply by 10, your learners could be missing out. ![]()
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