Математика 3 класс Г.В.Дорофеев, Т.Н.Миракова, Т.Б.Бука Номер 8

(160 + 290) : 9 = 450 : 9 = 50
1)

\begin{array}{r} \begin{array}{r} + \end{array} \begin{array}{r} 160 \\ 290 \end{array} \\ \begin{array}{r} 450 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 450 \\ \underline{45} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 9 \\ \bar{50} \end{array} \end{matrix}

.

(190 + 300) : 7 = 490 : 7 = 70
1)

\begin{array}{r} \begin{array}{r} + \end{array} \begin{array}{r} 190 \\ 300 \end{array} \\ \begin{array}{r} 490 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 490 \\ \underline{49} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 7 \\ \bar{70} \end{array} \end{matrix}

.

(180 + 380) : 8 = 560 : 8 = 70
1)

\begin{array}{r} \begin{array}{r} + \end{array} \begin{array}{r} 180 \\ 380 \end{array} \\ \begin{array}{r} 560 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 560 \\ \underline{56} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 8 \\ \bar{70} \end{array} \end{matrix}

.

(750 − 190) : 4 = 560 : 4 = 140
1)

\begin{array}{r} \begin{array}{r} - \end{array} \begin{array}{r} 750 \\ 190 \end{array} \\ \begin{array}{r} 560 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 560 \\ \underline{4} \\ \underline{} 16 \\ \underline{16} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 4 \\ \bar{140} \end{array} \end{matrix}

.

(900 − 180) : 6 = 720 : 6 = 120
1)

\begin{array}{r} \begin{array}{r} - \end{array} \begin{array}{r} 900 \\ 180 \end{array} \\ \begin{array}{r} 720 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 720 \\ \underline{6} \\ \underline{} 12 \\ \underline{12} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 6 \\ \bar{120} \end{array} \end{matrix}

.

(860 − 290) : 3 = 570 : 3 = 190
1)

\begin{array}{r} \begin{array}{r} - \end{array} \begin{array}{r} 860 \\ 290 \end{array} \\ \begin{array}{r} 570 \end{array} \end{array}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 570 \\ \underline{3} \\ \underline{} 27 \\ \underline{27} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 3 \\ \bar{190} \end{array} \end{matrix}

.

340 * 2 − (810 : 9 + 110) = 680 − (90 + 110) = 680 − 200 = 480
1)

\begin{matrix} \begin{array}{l} \underline{} 810 \\ \underline{81} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 9 \\ \bar{90} \end{array} \end{matrix}

;
2)

\begin{array}{r} \begin{array}{r} + \end{array} \begin{array}{r} 90 \\ 110 \end{array} \\ \begin{array}{r} 200 \end{array} \end{array}

;
3)

\begin{array}{r} \times \underline{\begin{array}{r} 340 \\ 2 \end{array}} \\ 680 \end{array}

;
4)

\begin{array}{r} \begin{array}{r} - \end{array} \begin{array}{r} 680 \\ 200 \end{array} \\ \begin{array}{r} 480 \end{array} \end{array}

.

(560 : 8 + 330 : 3) * 5 = (70 + 110) * 5 = 180 * 5 = 900
1)

\begin{matrix} \begin{array}{l} \underline{} 560 \\ \underline{56} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 8 \\ \bar{70} \end{array} \end{matrix}

;
2)

\begin{matrix} \begin{array}{l} \underline{} 330 \\ \underline{3} \\ \underline{} 3 \\ \underline{3} \\ \underline{} 0 \\ \underline{0} \\ 0 \end{array} & \begin{array}{l} 3 \\ \bar{110} \end{array} \end{matrix}

;
3)

\begin{array}{r} \begin{array}{r} + \end{array} \begin{array}{r} 70 \\ 110 \end{array} \\ \begin{array}{r} 180 \end{array} \end{array}

;
4)

\begin{array}{r} \times \underline{\begin{array}{r} 180 \\ 5 \end{array}} \\ 900 \end{array}

.

999 − 200 * (72 : 18) = 999 − 200 * 4 = 999 − 800 = 199
1) 72 : 18 = 4;
2) 200 * 4 = 800;
3) 999 − 800 = 199.

Математика 3 класс Г.В.Дорофеев, Т.Н.Миракова, Т.Б.Бука