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I just want to say that i may have wrong, i answer with the knowledge i have. I'm an amateur and by no mean one of those "bitcoin experts".So.We have 6 (uncompressed) public keys (it's just there for the example, don't use them, they are empty)alice0469cfc33bfed0c3e573e1b3b26395f3cd86e4f7d357c2a325f4d0f44d39486fd9c70edb4126e035f617c8bbeae934325e173f4acf9001b73b5b3d79659777a29bbob04c894e9fb4aefd48ffcbc165b1926d0cb74ea39e279f20e966a78cca346358dfa053ed8f7e75790415dbf719a5d1e1ec9feaad0fa52497f5b8b5c92e717f0ce9fcharlie049e3e61846822d308a233655bba8ca20fd92859a5e28914fc4049e1997b37212fe1c00d8c2aaf717c0be1e98ddd1f0b5f74bd180ce8997ea7b453a5e852646128dave04587d7b8f210294da8febae1915d8d1ffcb9b514b0ac7e7c67a6370f12dcee3cbec0f53021c9e48e19e7f3db8f524d75f0255645813fd54962a07bb6b6ff5ef2beve0449cd6e102bf602ad4b7830c625ed26aebca8577e685691d4494f895904bfae4c8894d6398d495bc7773da6f81615ae29a810c8d6f09605ec1e961a61361065dafrank04025ef509facb718363849676fdc6255341abacb4378f2da6a117da4a6ade1cd8feff2405dc5fbd2dcd09a32481449bc84d1b6e5e589810f0e64691ca7e31e674We require that 3 persons (of the 6) must sign the transaction to be able to spent the coins.The MofN redeem script will be: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 details:53 (OP_3) the minimum signatures required41 (public key length in byte)0469cfc33bfed0c3e573e1b3b26395f3cd86e4f7d357c2a325f4d0f44d39486fd9c70edb4126e035f617c8bbeae934325e173f4acf9001b73b5b3d79659777a29b (alice's public key)41 (public key length in byte)04c894e9fb4aefd48ffcbc165b1926d0cb74ea39e279f20e966a78cca346358dfa053ed8f7e75790415dbf719a5d1e1ec9feaad0fa52497f5b8b5c92e717f0ce9f (bob's public key)41 (public key length in byte)049e3e61846822d308a233655bba8ca20fd92859a5e28914fc4049e1997b37212fe1c00d8c2aaf717c0be1e98ddd1f0b5f74bd180ce8997ea7b453a5e852646128 (charlie's public key)41 (public key length in byte)04587d7b8f210294da8febae1915d8d1ffcb9b514b0ac7e7c67a6370f12dcee3cbec0f53021c9e48e19e7f3db8f524d75f0255645813fd54962a07bb6b6ff5ef2b (dave's public key)41 (public key length in byte)0449cd6e102bf602ad4b7830c625ed26aebca8577e685691d4494f895904bfae4c8894d6398d495bc7773da6f81615ae29a810c8d6f09605ec1e961a61361065da (eve's public key)41 (public key length in byte)04025ef509facb718363849676fdc6255341abacb4378f2da6a117da4a6ade1cd8feff2405dc5fbd2dcd09a32481449bc84d1b6e5e589810f0e64691ca7e31e674 (frank's public key)56 (OP_6) the total of public keys the script containae (OP_CHECKMULTISIG)That script is then computed with SHA256 then with RipeMD160. Those computations give us the hash1:e552b89fce59a48ff73957b438282225fe02aa46We then take the Bitcoin script hash prefix 05 and we add it at the start of the previous hash1:05e552b89fce59a48ff73957b438282225fe02aa46Now, we compute two time those bytes with SHA256 and get the hash2:316a2f23ea5b77e024b8d66d38e9dbc2d1570dec533165304a3e07794aac9f26We take the 4 first bytes from hash2 and add them at the end of hash1 to get:05e552b89fce59a48ff73957b438282225fe02aa46316a2f23Finally, we compute those bytes with Base64 and we get the address:3NbZm3P43K3CyktRm9S171iJau5XRCgqTxYou can check here: https://coinb.in/multisig/ All that to say, when you send coins to a multisig address, you lock these coins with the hash we just computed and "stored" on the address.To create a transaction spending those coins, you need to provide the redeem script in it for the transaction can be validated by the network. Before checking the signatures, every node compute the hash for the given redeemscript and check it with the previous transaction scriptpublickey which contain the locking hash. So, logically, if you have lost 2 of the 6 public keys used to create the redeem script, you wont be able to build the entire redeem script, get the right hash and therefor, wont be able to successfully spend the coins.I hope i didn't given too much details or anything, i have a hard time to know when i have to stop