Adding and subtracting integers on a number line

MathematicsNumbers & ArithmeticAges 11–12

A number line with two arrows: the blue arrow goes from 0 to a, and the red arrow continues b steps further (to the right for adding a positive number, to the left for adding a negative one; subtraction turns into adding the opposite). Drag the arrow tips to change a and b and see the calculation and result update instantly; turn on absolute value to compare the arrow lengths.