A straightforward mental arithmetic page on adding decimals. The process is very much the same as adding two 2-digit whole numbers. When adding in our heads we usually start with the largest numbers, which, of course, is the opposite of the way we do it on paper. This needs pointing out to children as many, even in Year 6, lack the strategies necessary for mental addition.
When adding 3 decimals there are several different strategies that can be used, including:
looking for pairs that make 1
starting with the largest number
counting on
knowing doubles etc.