Fifth grade volume two math score exercises with 20 answers!

Fifth grade volume two math score exercises with 20 answers!

*It's a multiple sign
1/5*4=4/5
2/7*3=7/6
2/21*5=10/21
1/11*3=3/11
1/8*5=5/8
5/18*3=5/6
1/4*2=1/2
2/13*4=8/13
4/17*3=12/17
6/19*3=18/19
7/23*3=21/23
4/27*5=20/27
1/8*4=1/2
1/7*3=3/7
5/12*2=5/6
4/7*14=8
2/15*3=2/5
1/4*20=5
4/5*20=16
5/18*3=5/6

dm2 dm3 cm cm2 cm3 ml L
Better draw a table!

Length unit: DM decimeter cm cm 1dm = 10cm area unit: DM2 square decimeter cm2 square centimeter 1dm2 = 100cm2 volume unit: DM3 cubic decimeter cm3 cubic centimeter 1dm3 = 1000cm3 volume & volume: l liter ml ml 1L = 1000ml = 1dm3 = 1000cm3 length unit is generally "full decimal one", kilometer

What do these symbols mean in fifth grade mathematics?

Some of them are defined new operation symbols. You can find them according to the rules defined by them
For example, a △ B = AB + 2B
Then 3 △ 4 = 3 × 4 + 2 × 4 = 12 + 8 = 20