: 1) ;
2) .
3) ;
4) ;
5)
1.
2.
3.
4.
() 2, 4, 1, 3, 7.
2. .
16 - 14 30 = 15 60 - 14 30 = 1 30
3. 12 20 .
20 + 31 + 28 + 20 = 99 (.) 20 + 31 + 29 + 20 = 100 (.)
4. .
) 3 , 10 , 18 , 23 ;
) 2 , 7 , 10 , 15 .
7.
(2 ∙ 30 +20) ∙ 9 = 720
2 ∙ (30+ 20 ∙ 9) = 420
2 ∙ 30 + 20 ∙ 9 = 240
2 ∙ (30 + 20) ∙ 9 = 900
5.
() 9, 8, 6*, 5, 10.
5.
1) 800: 2 = 400 (.) ;
2) 400 4 = 1600 (.) .
6*. , 60. : 60, 120, 180 . .
9. 1002, 1001, 1000 .
10.
- 100 - 100 - 100 - 100 = 500;
= 500 + 400;
= 900.
6. () 11, 12.
11.
5 ∙ 624 = 3120 ();
4 692 = 2768 ();
3120 - 2768 = 352 ().
7.
8.
28
. . .
: 1) ;
2) .
3) ;
4) ;
5)
1.
2.
3.
4.
() 9, 1, 2, 5, 6*.
1. 1917 () 19 17 20- ; 1995 20- ; 21- ; 20- 1901 ; 21- 2001 .
5. , . : 12 > 5000 , 1 1000 , 12 12 000 , 12 000 > 5000 .
6*. 12 . 6 , 2 . (13).
:
12 + 1 = 13 11 + 2 = 13
10 + 3 = 13
9 + 4 = 13 8 + 5 = 13
7 + 6 = 13
5.
() 4, 3, 7, 8, 10, 11.
3.
½ = 12 ; ⅓ = 8 ; 1/6 = 4 ;
½ = 30 ; ⅓ - 20 ; ¼ = 15 ;
|
|
1/5 = 12 ; 1/6 = 10 ; 1/10 = 6 .
4. 80 400, 804 000, 7070.
7. : ?
1 440 = 1440 .
?, ⅓ .
75 .
?
1) 1440: 3 = 480 (); I
2) 480 + 75 = 555 ();
3) 1440-555 = 885 ().
10. F
. ,
.
DFE.
11. : + 730 = 1000;
= 270.
270.
) 12, 13.
12.
(12 4): 6 = 8 ()
7.
8.
29