1, the big three digits composed of 1, 5 and 7 are (), and the small three digits are (). Their difference is ().
[Resolution] Use a three-digit number consisting of 1, 5, and 7, with a high digit of 7, a decimal digit and a unit digit of 5 and1respectively; To use three digits consisting of 1 and 5.7, the high-order digit is 1, and the tenth digit and unit digit are 5 and 7 respectively; Then, according to the calculation method of integer subtraction, find out what the difference is.
[Solution] Solution: The big three digits consisting of 1, 5 and 7 are 75 1, and the small three digits are 157. Their difference is: 75 1- 157=594.
2. Fold a 4m-long rope twice, and then cut it along the crease. Now each length is () cm. If folded three times, the length of each time is () cm.
[Analysis] After a 4-meter-long rope is folded in half twice, it is divided into four sections on average, and folded in half three times, that is, the rope is divided into eight sections on average, from which the answer can be obtained.
[Solution] Solution: 4 decimeters =40 cm
40=4= 10 (cm)
40:8=5 cm
3. Popular folk songs and operas in Longyan area of western Fujian are mainly sung in Longyan dialect. The experimental primary school organizes the third and fourth grades to watch folk songs and operas. Grade three 177 students, grade four 238 students. There are 420 seats in this theater, and all the seats are full. (Fill in "Can" or "Can't")
[Analysis] Add up the figures of the two grades and compare them with 420, and you can get the answer.
[Solution] Solution: 177+238 =4 15 (person)
4 15 & lt； 420
A: The theater has 420 seats, all of which can be taken.
So the answer is: yes.
4. The human skeleton consists of skull, trunk bone, upper limb bone and lower limb bone. There are 206 bones in the human body, including 29 skulls, and the upper limb bones are more than the trunk bones 13, () upper limb bones and () lower limb bones.
[Analysis] Using the number of trunk bones and the number of upper limb bones more than trunk bones, we can find out how many trunk bones there are. According to the significance of subtraction, the number of skull, trunk bone and upper limb bone can be subtracted from the total number of blocks to get the number of lower limb bones.
[Solution] Solution: 5 1+ 13 =64 (block)
206-29-5 1-64= 62 (block)
A: There are 64 upper limb bones and 62 lower limb bones.
So the answer is: 64, 62.
5. When calculating the subtraction, Tao Tao writes 5 in the tenth place of the minuend as 8, and the difference obtained by writing 5 in the decimal place as 8 is 68. The correct difference is () [Analysis] According to the meaning of the question, the 5 in the tenth place of the minuend is regarded as 8, so the error difference is increased by 80-50=30 compared with the original correct result.
Five of the meiotic units is considered to be eight. The greater the meiosis, the smaller the difference, and the difference will be reduced: 8 -5=3, so the wrong difference is reduced by 3 compared with the original correct difference; Therefore, the correct difference is 50-3 = 47 higher than the current result; Then 67 minus the increased 47 is the correct result.
[Solution] Solution: 68-(80 -50)+(8-3)=68-30+5=43.
A: The correct difference is 43.
So the answer is: 43.