1000000000 // Is this a billion? a hundred millions? Ten millions? 101475938.38 // what scale is this? what power of 10? const FEE = 12300; // is this 12,300? Or 123, because it's in cents? const AMOUNT = 1234500; // is this 1,234,500? Or cents, hence 12,345? Or financial, 4-fixed 123.45? 1_000_000_000 // Ah, so a billion 101_475_938.38 // And this is hundreds of millions let fee = 123_00; // $123 (12300 cents, apparently) let fee = 12_300; // $12,300 (woah, that fee!) let amount = 12345_00; // 12,345 (1234500 cents, apparently) let amount = 123_4500; // 123.45 (4-fixed financial) let amount = 1_234_500; // 1,234,500 0.000001 // 1 millionth 0.000_001 // 1 millionth .000_001 // 1 millionth -.000_001 // 1 millionth 1e10_000 // 10^10000 -- granted, far less useful / in-range... let nibbles = 0b1010_0001_1000_0101; let message = 0xA0_B0_C0; let x1 = _52; // This is an identifier, not a numeric literal let x2 = 5_2; // OK (decimal literal) let x7 = 0x5_2; // OK (hexadecimal literal) 0xff 0xdead_beef 0o52 0O52 0xa 0Xa 0XA 0xA 0n 2n 20n 2_0n 2_00n 2_0_0n 20_0n -20_0n