ex.1   Calculati dupa modelul dat:
1 176-9=(1 176-10)+1              1 176-90=(1 176-100)+10
            =1 166+1                                    =1 076+10
            =1 167                                        =1 086

a).2 248-9=                  b).3 637-9=               c).6 600-9=
    2 248-90=                    3 637-90=                  6 600-90=

Răspuns :

a)2248-9=(2248-10)+1=2238+1=2239
2248-90=(2248-100)+10=2148+10=2158
b)3637-9=(3637-10)+1=3627+1=3628
3637-90=(3637-100)+10=3537+10=3547
c)6600-9=(6600-10)+1=6590+1=6591
6600-90=(6600-100)+10=6500+10=6510