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一、在$\boxed{□}$里填上适当的数，在$◯$里填上适当的运算符号。
$42.58 - 0.6 - 0.4 = 42.58 - (\boxed{□}◯\boxed{□})$
$19.92 + 71.5 - 9.92 = 19.92 - \boxed{□} + \boxed{□}$
$7.36 + 2.53 - 0.36 = 7.36 ◯\boxed{□}◯2.53$
$12.3 + (7.8 + 7.7) = \boxed{□} + \boxed{□} + \boxed{□}$
$5.38 - 2.34 - 1.66 = 5.38 - (\boxed{□}◯\boxed{□})$
$42.58 - 0.6 - 0.4 = 42.58 - (\boxed{□}◯\boxed{□})$
$19.92 + 71.5 - 9.92 = 19.92 - \boxed{□} + \boxed{□}$
$7.36 + 2.53 - 0.36 = 7.36 ◯\boxed{□}◯2.53$
$12.3 + (7.8 + 7.7) = \boxed{□} + \boxed{□} + \boxed{□}$
$5.38 - 2.34 - 1.66 = 5.38 - (\boxed{□}◯\boxed{□})$
答案
0.6 + 0.4 9.92 71.5 - 0.36 + 12.3 7.7 7.8 2.34 + 1.66
二、计算下面各题，怎样简便就怎样计算。
4.04-2.5+0.96
8.25-(7.25-0.66)
1-0.01-0.02-0.03-…-0.08-0.09
99+9.9+0.99+0.999+1.111
4.04-2.5+0.96
8.25-(7.25-0.66)
1-0.01-0.02-0.03-…-0.08-0.09
99+9.9+0.99+0.999+1.111
答案
2.5
1.66
0.55
112
1.66
0.55
112
