The Sign Rules from a Pattern: Multiplying Signed Numbers

You cannot repeat something minus three times — so what is minus three times minus two? Two tables answer it. In the first, the second factor goes down by one at each line and the product goes down by three, right past zero: a positive times a negative gives a negative. In the second, the product goes up by two at each line, past zero again: a negative times a negative gives a positive. Then the rule — multiply the distances to zero, then decide the sign — on two examples, and your turn: minus four times plus six. Timestamps: 0:00 — Not a number of repetitions 0:38 — Down by three 1:36 — Up by two 2:38 — The rule 3:21 — Example: (+2) × (−5) 3:40 — Example: (−7) × (−4) 3:58 — Your turn 4:22 — Let's remember 🎓 Free interactive lesson: https://commeunjeu.org/cours/ib-myp-1... ▶️ The whole series “Integers”:    • Integers   🎵 Music: "Ever Mindful" by Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 4.0 http://creativecommons.org/licenses/b...