KwickClips Python · 43 sec · free
Why does factorial start at 1?
Short answer. Multiplying by 0 would make it 0.
Where does a sum start?
At 0.
Same loop, three jobs
| Program | Start value | Inside loop |
|---|---|---|
| Table of 7 | none | print 7 * num |
| Factorial 5 | fact = 1 | fact * num |
| 1 + 3 + ... 19 | total = 0 | total + num |
Remember
| Multiply: start at 1 |
| Add: start at 0 |
Three programs, one loop idea. What changes? Each loop takes num from a range. The table prints seven times num. Factorial starts at one and multiplies. The series starts at zero and adds. Multiply, start at one. Add, start at zero.
This clip is from the full lesson: for Loop and range() — 8 minutes, with the tables, the quick answers and the whole lesson in text.
Useful for: CBSE Class 11 Computer Science (083), CBSE Class 11 Computer Science Essentials (083), CBSE Class 11 Informatics Practices (065), Programming All levels Python
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