9=72 8=56 7=42 6=30 5=20 3=?
9=72 8=56 7=42 6=30 5=20 3=?
3/8+13/18= 5/6+8/9= 2/7+1/3= 7/12-3/8=
{}+{}={}{}—{}={} {}*{}={} 1,2,3,4,5,6,7,8,9,0.
5+3=28 9+1=810 8+6=214 5+4=19
3/2-5/6+7/12-9/20+11/30-13/42=()
1=10 2=20 3=30 4=40 5=50
1+2/1-6/5+12/7-20/9+30/11-42/13+56/15-72/17=?
(1)计算并观察下列每组算式:8×8=7×9=,5×5=4×6=,12×12=11×13=;
根据下面一组等式:S 1 =1;S 2 =2+3=5;S 3 =4+5+6=15;S 4 =7+8+9+10=34;S
=
=?
8:( )=( ):20=5分之4=( )÷30=几分之16.