Bug in windows calculator (10 * 10 + 10 * 10 = 1100)

Not a bug.

In standard mode Windows calculator does the operations in order (just like most handheld non-scientific calculators). You're doing (10 * 10), ((10 * 10) + 10), (((10 * 10) + 10) * 10).

I don't think so. What the calculator does is simply (((10 * 10) + 10) * 10) like a basic pocket calculator.

its funny how people never realized that calculators only do what they are told, unless you insist on the calculator doing 10 * 10 and then 10 * 10 and then putting those two results together. :)

The calculator won't use BIDMAS by default, as far as I know. So it may not be a bug.

200 in scientific mode