Estimate the product 80 * 26

You estimate it to be 80 times 30 because it is easier to do. This equals 240.

Looks long but it is very fast actually

26 is 25+1

Multiply by 25 is like * 100 and / 4 (because 25=100/4)

So you can see very quick that 80 * (25+1) equals 80*25+80

which is 80*100/4+80 or 80/4*100+80

So it equals 20*100+80 which you can calculate very fast to 2080

Hope you see how this is done fast