4 ms·

I used a calculator the other day to do 73 - 52, yet I can pass a third year university algebra course. Sure, tables are useful, but they are very far from the

I used a calculator the other day to do 73 - 52, yet I can pass a third year university algebra course. Sure, tables are useful, but they are very far from the be-all-end-all of primary school education, which they very much were for me when I was younger (you were good or bad at maths based on how good you were at your times-tables, which is hardly a good way to motivate people who enjoy mathematics, but don't excel at rote memorisation)

sitkack 12y ago
That diagram was teaching the fungibility of numbers. Afaik CC doesn't say that these things _must_ be taught this way. To solve your problem with the same technique as the article, you would have added 1 to 52, 73 - 53 = 20, then + 1 for the answer. You would need to know ball park anyway to see if the calculator answer made sense.