Question

估算． 5.6×9.8≈	41÷4.9≈	55.8÷8.02≈
36.2÷3.96≈	0.79×5.02≈	9.98×5.8≈

Answer 1

解：5.6×9.8≈6×10=60	41÷4.9≈40÷5=8	55.8÷8.02≈56÷8=7
36.2÷3.96≈36÷4=9	0.79×5.02≈1×5=5	9.98×5.8≈10×6=60

分析：在除法估算中，一般要根據(jù)“四舍五入”法，把被除數(shù)看作是能被，除數(shù)整除的整十、整百、或幾百幾十…的數(shù)來進(jìn)行計(jì)算，若是小數(shù)，一般把小數(shù)看作整數(shù)來進(jìn)行計(jì)算；在乘法估算中一般要根據(jù)“四舍五入”法，把因數(shù)看作是整十、整百、整千…的數(shù)來進(jìn)行計(jì)算．若因數(shù)是小數(shù)，一般也把它看作整數(shù)來進(jìn)行計(jì)算．
點(diǎn)評：本題考查了學(xué)生在除法估算和乘法估算中，都要用“四舍五入”法，來進(jìn)行估算．