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Number bases
Converting between decimal, binary, octal and hexadecimal.
A base-b number is a sum of powers of b. To convert from decimal, divide by b repeatedly; the remainders, read from the last to the first, are the digits. Binary (base 2) and hexadecimal (base 16) are how computers store every number you see.
ຕົວຢ່າງທີ່ໄດ້ເຮັດ · 255 to binary
ຂັ້ນຕອນຕໍ່ຂັ້ນຕອນ
- 255_{10} \to \text{base } 2
Repeatedly divide by 2; the remainders, read bottom-up, are the digits.
- 255 = 127 \times 2 + 1
remainder 1
- 127 = 63 \times 2 + 1
remainder 1
- 63 = 31 \times 2 + 1
remainder 1
- 31 = 15 \times 2 + 1
remainder 1
- 15 = 7 \times 2 + 1
remainder 1
- 7 = 3 \times 2 + 1
remainder 1
- 3 = 1 \times 2 + 1
remainder 1
- 1 = 0 \times 2 + 1
remainder 1
ເປີດເຜີຍຄຳຕອບ
ປັດຈຸບັນທ່ານ ເລືອກບັນຫາ ຫຼື ພິມ ຫຼື ແຕ້ມເອງ. ທຸກບາດກ້າວ, ຮູບ, ຄໍາຕອບຖືກລົບຈົນກວ່າເຈົ້າຈະຖາມມັນ.
ຕົວສະແດງທີ່ໃຊ້ຢູ່ທີ່ນີ້
ກົດຕົວອັກສອນໃດໜຶ່ງເພື່ອເບິ່ງຄວາມໝາຍເຕັມ, ຮູບ ແລະ ຕົວອັກສອນແຕ່ລະຕົວໃນມັນໝາຍຄວາມວ່າແນວໃດ.
ວິທີການ: Number bases
- Repeatedly divide by 2; the remainders, read bottom-up, are the digits.
- remainder 1
- remainder 1
- remainder 1
- remainder 1
- remainder 1
- remainder 1
- remainder 1
ຄໍາຖາມທີ່ຄົນຖາມ
Why are primes so important?
Every integer factors into primes in exactly one way, so primes are the atoms of multiplication. Cryptography relies on that factoring being easy to state and hard to do.
How do I tell whether a big number is prime?
Trial division up to the square root works for small numbers. For large ones, probabilistic tests (Miller-Rabin) give an answer that is wrong with negligible probability, and deterministic tests (AKS) exist but are slower.
ເພີ່ມເຕີມໃນ Number Theory
Prime factorisationPrime numbersGCD and LCMModular arithmeticDivisorsSequencesDiophantine equationsFermat's little theorem and Euler's theoremRSA: cryptography from number theory