Estimating is designed to be an educated guess either to (a) access prior knowledge or to (b) evaluate the reasonableness of an answer . For each of the following estimation strategies:
For two highest place values only.
Why round up on a 5, but down on a 4?
The techniques for mental arithmetic are related to estimation techniques, only the accuracy of the final answer is in question. For each of the following mental math strategies:
Why doesn't this say "add zeros"?
All place values.