For example:
The direct addition and subtraction within 100 includes: 3+43 = 30+43 = 36+3 = 36+30 = 65-33 = 65-3 = 4+34 = 7+32 = 6+62 = 60+26 = 76-4 = 76. 3-23= 73-2= 62+26= 88-26= 20+65= 2+65= 93- 1= 93- 1 0= 64-3= 64-30= 55-44= 32+23= 7+72= 72-42= 60-40= 50+20= 6+53= 60+35= 23+23= 42+24= 67-35= 59-26= 32+46 2+56= 20+56= 1+36= 1 0+36= 72-2= 72-20= 68-35= 96-55= 83-52= 33+22= 55-32= 55-23= 69-25= 46-26= 2 1+ 12= 36+62= 5654 38+0+42= 8 1+ 1 7= 62-22= 44+ 1 1= 66+22= 88-55= 77- 1 1= 8+ 1 1= 80+ 1 1= 99-66= 55- 1 4= 29-6543 8+06= 9+70= 6+40= 4+30= 40+30= 7+70= 88-6= 75-3= 44+33= 77-44= 66-33= 5+50= 7+4 1= 57- 17= 62+36= 80-40= 5 1+ 1 5= 22+77= 22+44= 44+ 44= 88-44= 66-44= 66-22= 78-26= 1 1+44= 55- 1 1 = 55-44= 55-22= 77-44= 33+44= 77-33= 36+63= 77-66= 6+52= 3+40= 55-2= 68-46= 28-6543 8+04= 35+53= 47+22= 82+ 17= 79-46= 5 1+ 1 8= 72-20= 53+ 12= 33- 1 1= 44+55= 99-55= 5+24= 0+53= 76-0= 66- 1 1 = 66 -55= 65-25= 73+23= 54+34= 68-42= 96-65= 9+90= 99-6= 35+6 1= 26+53= 70-50= 55-25= 40+53= 98-25= 7 1-2 1 = 42+56= 78-56= 63+34= 78-55= 64-5 3= 75-63= 77-74= 22+56= 67+22= 56+ 10= 89-87= 63-52= 98-9 1= 24+75= 88+ 1 1= 60+6=