Simple calculation of (18.73-2 + 1 / 2 + 3 / 5) × (4.4-4 + 2 / 5) + 6 + 8 / 9

Simple calculation of (18.73-2 + 1 / 2 + 3 / 5) × (4.4-4 + 2 / 5) + 6 + 8 / 9

4.4-4 and 2 / 5 equals zero, so the front one is zero, and the result is 6 and 8 / 9

Simple operation of 18 △ 1.5-0.5 × 0.3 simple operation of 8.5 + (5.6-4.8) × 13

These two problems are not complex, slightly deformed, and then calculated directly
18÷1.5-0.5×0.3=18×(2/3)-0.015=12-0.015=11.985;
8.5+（5.6-4.8）×13=8.5+0.8×13=8.5+10.4=18.9.

Simple calculation of 4 * 4 of 3 * 5 + 6 * 6 of 5 * 7 + 18 * 18 of 17 * 19

4 * 4 of 3 * 5 = 1 + 1 / (3 * 5) = 1 + 1 / 2 * (1 / 3-1 / 5)
and so on:
8+1/2*(1/3-1/19)
Count the rest

Simple calculation of (18.6-18.6 △ 3.1) × 0.4

（18.6-18.6÷3.1）×0.4
=(18.6-6)x0.4
=12.6x0.4
=12.5x0.4+0.1x0.4
=5+0.04
=5.04