38 * x, если x = 10, 8, 5;
1) При x = 10:
38 * 10 = 380
2) При x = 8:
38 * 8 = (30 + 8) * 8 = 30 * 8 + 8 * 8 = 240 + 64 = 304
$\snippet{name: op_column, sign: '+', x: '240', y: '64', z: '304'}$
3) При x = 5:
38 * 5 = (30 + 8) * 5 = 30 * 5 + 8 * 5 = 150 + 40 = 190
$\snippet{name: op_column, sign: '+', x: '150', y: '40', z: '190'}$

409 + y, если y = 302, 501, 511;
1) При y = 302:
409 + 302 = 711
$\snippet{name: op_column, sign: '+', x: '409', y: '302', z: '711'}$
2) При y = 501:
409 + 501 = 910
$\snippet{name: op_column, sign: '+', x: '409', y: '501', z: '910'}$
3) При y = 511:
409 + 511 = 920
$\snippet{name: op_column, sign: '+', x: '409', y: '511', z: '920'}$

a – 199, если a = 200, 800, 1 000;
1) При a = 200:
200 − 199 = 1
$\snippet{name: op_column, sign: '-', x: '200', y: '199', z: '1'}$
2) При a = 800:
800 − 199 = 601
$\snippet{name: op_column, sign: '-', x: '800', y: '199', z: '601'}$
3) При a = 1000:
1000 − 199 = 801
$\snippet{name: op_column, sign: '-', x: '1000', y: '199', z: '801'}$

n : 7, если n = 140, 280, 980
1) При n = 140:
140 : 7 = 20
$\snippet{name: long_division, x: 140, y: 7}$
2) При n = 280:
280 : 7 = 40
$\snippet{name: long_division, x: 280, y: 7}$
3) При n = 980:
980 : 7 = 140
$\snippet{name: long_division, x: 980, y: 7}$