I find it interesting that in the UK a primary school child (say aged about 7) would trivially know that "80 + 4" is 84, but for the problem "4 x 20 + 10 + 7 = ?", might require quite a lot of effort to work out that the answer is 97.
In France, "97" is said "Quatre vinght dix sept", i.e. 4x20+10+7. This is apparently acceptable to the brain as a final answer, there's no way to collapse it to "90+7".
In France, "97" is said "Quatre vinght dix sept", i.e. 4x20+10+7. This is apparently acceptable to the brain as a final answer, there's no way to collapse it to "90+7".