问题
解答题
用简便方法计算.
|
答案
(1)25×24,
=25×4×6,
=100×6,
=600;
(2)(27×5)×2,
=27×(5×2),
=27×10,
=270;
(3)263+65+35+337,
=263+337+(65+35),
=600+100,
=700;
(4)800÷25,
=8×100÷25,
=8×(100÷25),
=8×4,
=32.
用简便方法计算.
|
(1)25×24,
=25×4×6,
=100×6,
=600;
(2)(27×5)×2,
=27×(5×2),
=27×10,
=270;
(3)263+65+35+337,
=263+337+(65+35),
=600+100,
=700;
(4)800÷25,
=8×100÷25,
=8×(100÷25),
=8×4,
=32.
下表是某农业研究所收集到酸雨对水稻收成影响的有关数据:
酸雨的pH | 3.58 | 4.59 | 4.86 | 7 |
水稻减产(%) | 10 | 5 | 3 | 0 |
A.水稻产量随酸雨的pH增加而减少
B.水稻产量随酸雨的pH减少而减少
C.酸性越强,水稻产量越高
D.水稻适合在酸性土壤中生长