If you type 1+2+3= in iOS 11.1’s Calculator app quickly, you may get 24 instead of 6. The problem is a delay in recognizing taps on all the operation buttons. Thus, in the example above, the second + is ignored, so you’ve instead typed 1+23=. If you type 1+2+3= slowly, making sure that the operator button activates on each tap, Calculator works correctly. We hope Apple fixes this embarrassing bug in the next update to iOS 11. In the meantime, Siri works well for simple calculations, and for those who need a serious calculator, PCalc is the gold standard.