L2 · Subtracting integers

Learning goal

“I can subtract any integer from any integer: subtracting a positive is adding a negative, and subtracting a negative is adding a positive - and I can show both on the number line and with zero pairs.”

Difference — the result of a subtraction; on the number line it is where you land after the move.

Additive inverse — the opposite of a number: the value that makes a zero pair with it (the inverse of -6 is 6). Subtracting a number means adding its inverse.

Integer — a whole number that can be positive, negative, or zero.

Worked example

Subtract -26 - 14. Step 1: A difference is a sum in disguise. Subtracting 14 is the same move as adding -14: -26 - 14 = -26 + (-14). Step 2: Now it is a same-sign addition: magnitudes add, sign stays negative: -26 + (-14) = -40. Step 3: The line agrees: start at -26, subtracting a positive moves LEFT 14: land on -40. The counter mat agrees too: 26 negative counters joined by 14 more negative counters. Say it plainly: every subtraction in this unit becomes an addition before we compute.

Check yourself — explain it

-26 - 14 moves left because...

Paired problem — example still visible

18 - 30 -> rewrite: 18 + (-30) = -12

Faded completion — last step is yours

"-45 - 12 = -45 + (___) = ___" -> -12; -57

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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