【1】 A cuboid oil tank is 4 decimeters wide and 30 centimeters high. How many square decimeters of iron sheet does it need to make this oil tank? If 0.8kg/l diesel is calculated, how many kilograms of diesel can this tank hold at most? 【2】 How many hours does it take for a car to travel 180 kilometers in three hours from place a to place B? 【3】 Convert to fraction (1) 25% off (2) buy 3 get 1 free (3) buy 5 get 2 free

【1】 A cuboid oil tank is 4 decimeters wide and 30 centimeters high. How many square decimeters of iron sheet does it need to make this oil tank? If 0.8kg/l diesel is calculated, how many kilograms of diesel can this tank hold at most? 【2】 How many hours does it take for a car to travel 180 kilometers in three hours from place a to place B? 【3】 Convert to fraction (1) 25% off (2) buy 3 get 1 free (3) buy 5 get 2 free

【1】 (5 * 4 + 5 * 3 + 4 * 3) * 2 = 94 (square decimeter)
5 * 4 * 3 * 0.8 = 48 (kg)
【2】 3 / (1 / 3) = 9 (hours)
【3】 (1) 25% discount = 75% = 3 / 4
(2) Buy 3 get 1 3 free / (1 + 3) = 3 / 4
(3) Buy 5 get 2 5 / (2 + 5) 5 / 7 free

1. How many digits is 2 ^ 11213-1?
2. Expressed by scientific counting method: 33 * 2 ^ 259
3. If n is a natural number, find the minimum number n such that 1.1 ^ n > 10 ^ 9

The first one upstairs is obviously wrong
2 ^ 3 is 8, not 10
His thinking should be similar to question 3
Because 2 ^ 10 = 1024
8 * 1.024 ^ 1121 > 10 ^ (n-3363)
In general, this problem is to look up the logarithm table and then look up
Question 3
Well, look it up or program it
I want to surrender

As shown in the figure, in △ ABC, the bisector of ∠ a = 90 ° intersects AB at D. if ∠ DCB = 2 ∠ B, calculate the degree of ∠ ADC

Let the bisector ab of ∠ B = x, ∵ - DCB = 2 ∠ B, ∵ - DCB = 2x, ∵ - C intersect at D, ∵ - ACD = ∠ DCB = 2x, ∵ - ADC is the outer angle of △ BCD, ∵ - ADC = ∠ B + ∠ DCB = 3x, in △ ACD, ∵ - A + ∠ ACD + ∠ ADC = 180 °, and ∵ - 90 ° + 2x + 3x = 180 °, the solution is x = 18 ° and ∵ ADC = 3x = 3