Show:
+1 within 20
-1 within 20
Doubles
Near doubles
Fun facts
100

3+1=

4

100

1-1=

0

100

2+2=

4

100

3+4=

7

100

25+25=

50

200

5+1=

6

200

6-1=

5

200

6+6=

12

200

6+5=

11

200

30+30=

60

300

10+1=

11

300

14-1=

13

300

7+7=

14

300

7+8=

15

300

100+100=

200

400

18+1=

19

400

18-1=

17

400
10+10=

20

400

8+9=

17

400

150+150=

300

500

13+1=

14

500

16-1=

15

500

9+9=

18

500

11+12=

23

500

350+220=

570