# Number and place value: topic summary

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It is important children should be able to count backwards and forwards along increasingly long number lines as they get older. Cardinal numbers give number names (1, 2, 3, 4 etc.) while ordinal numbers denote position (1st, 2nd, 3rd etc.). All whole numbers are called integers. Our number system is called the denary system because it is based on tens. Numbers increase ten-fold as they move from right to left. Children may experience some confusion as we read a number one way, 123 as one hundred and twenty three, while interpreting it in the other direction, 1 unit, 2 tens, 3 hundreds. Children should be able to read, write and identify numbers up to 10, 000, 000 by the end of Year Six. An important feature of the denary system is the use of zero as a place holder, as in 30 (thirty), 107 (one hundred and seven) and 3040 (three thousand and forty). The ability to round off numbers to the nearest 10, 100, 1000 etc. is very useful for estimating the answers to calculations.

Using a simple abacus is a good way of re-enforcing place value or ringing a single digit in a large number and asking the child to identify it e.g. 45723 with the 7 ringed. Alternatively, use the partition method e.g. 3716 broken down into 3000 + 700 + 10 + 6. You could also provide digit cards, say, 5, 4, 2, 0, 9 and ask children to make a range of different numbers using them e.g. 95420.