Subtraction quiz – 1 from other numbers. Interactive online math quiz to test children on subtraction skills; in this case children will learn to subtract the number one from other numbers for example, 5 – 1 = 4 and so on. The quiz is either gap-fills in some cases or MCQ. Simply solve each problem and choose or type in the correct answer. This exercise is for children in 1st, 2nd, 3rd, and 4th grades to review their math skills.