Decimals - ordering and rounding N1.1 Support Starter Jot down a two-digit number, for example, 43 Double the tens digit (8) and add 5 times the units digit (15) giving (8 + 15 =) 23. Double the tens digit (4) and add 5 times the units digit (15) giving (4 + 15 =) 19. Keep repeating these steps. What do you notice? Investigate other starting numbers. Preamble This activity is designed to reintroduce the idea of tens and units to pupils. Wherever practical allow them to discover for themselves that the numbers repeat. Accuracy is crucial, so reference may be made to the importance of checking calculations. The issue of how to handle numbers like 3 (i.e. 03) should be confronted if at all possible. Possible content Basic number work, pattern spotting, using tens and units in the context of a mini investigation. Resources None. Solutions/Notes The sequence repeats. For the example given, the sequence is 43 23 19 47 43 23 19 47 …