12 * 70 = 12 * 7 * 10 = 84 * 10 = 840;
 
26 * 30 = 26 * 3 * 10 = 78 * 10 = 780;
 
800 − 14 * 50 = 800 − 14 * 5 * 10 = 800 − 70 * 10 = 800 − 700 = 100;
 
400 + 27 * 30 = 400 + 27 * 3 * 10 = 400 + 81 * 10 = 400 + 810 = 1210;
 
900 − (17 * 20 − 640 : 2) = 900 − (340 − 320) = 900 − 20 = 880;
 
(324 + 18 * 30) : 8 * 9 = (324 + 18 * 3 * 10) : 8 * 9 = (324 + 54 * 10) : 8 * 9 = (324 + 540) : 8 * 9 = 864 : 8 * 9 = 108 * 9 = 972.
$\snippet{name: long_division, x: 864, y: 8}$
 
$\snippet{name: column_multiplication, x: 108, y: 9}$