user81586: I am struggling to find a simple explanation for how to create a multisig address. For single sig, it's clear: double hash function applied to the single pubic key in base code 59. I just can't find any clear explanation for the multisig. Help please.

user7272: A multisig address is simply a redeem script of the form m <keys> n OP_CHECKMULTISIG.
This redeem script is then wrapped in a P2SH address, which is the HASH_160 of the redeem script presented in the format standardised in BIP16
For instance, a common multisig address is 2of2 (2of3 is also very common). An example redeem script is 522103c9078b8d06d83347b2e7e8cbbdfc24bd50e09ca1a4e5d90d70485a8c4094e5672102d52317afd128305d6fca7bd30b839e821564990c88581ebb432b478cfa95602f52ae, which decodes to:
2 03c9078b8d06d83347b2e7e8cbbdfc24bd50e09ca1a4e5d90d70485a8c4094e567 02d52317afd128305d6fca7bd30b839e821564990c88581ebb432b478cfa95602f 2 OP_CHECKMULTISIG

Producing a HASH_160 for the above redeem script gives us 4aef67ed61d391d6f3d9903ead92386c1efc9925, which when put in the P2SH form is a914(4aef67ed61d391d6f3d9903ead92386c1efc9925)87 (brackets mine).
This finally gives us the address 38XEixUj1QpcqxTWbxvqdbv4Mjre4imw9Z after a Base58Check encode.

81586: <p>I am struggling to find a simple explanation for how to create a multisig address. For single sig, it's clear: double hash function applied to the single pubic key in base code 59. I just can't find any clear explanation for the multisig. Help please.</p>
 7272: <p>A multisig address is simply a redeem script of the form <code>m &lt;keys&gt; n OP_CHECKMULTISIG</code>.</p>

<p>This redeem script is then wrapped in a P2SH address, which is the HASH_160 of the redeem script presented in the format standardised in <a href="https://github.com/bitcoin/bips/blob/master/bip-0016.mediawiki" rel="nofollow noreferrer">BIP16</a></p>

<p>For instance, a common multisig address is 2of2 (2of3 is also very common). An example redeem script is <code>522103c9078b8d06d83347b2e7e8cbbdfc24bd50e09ca1a4e5d90d70485a8c4094e5672102d52317afd128305d6fca7bd30b839e821564990c88581ebb432b478cfa95602f52ae</code>, which decodes to:</p>

<pre><code>2 03c9078b8d06d83347b2e7e8cbbdfc24bd50e09ca1a4e5d90d70485a8c4094e567 02d52317afd128305d6fca7bd30b839e821564990c88581ebb432b478cfa95602f 2 OP_CHECKMULTISIG
</code></pre>

<p>Producing a HASH_160 for the above redeem script gives us <code>4aef67ed61d391d6f3d9903ead92386c1efc9925</code>, which when put in the P2SH form is <code>a914(4aef67ed61d391d6f3d9903ead92386c1efc9925)87</code> (brackets mine).</p>

<p>This finally gives us the address <code>38XEixUj1QpcqxTWbxvqdbv4Mjre4imw9Z</code> after a Base58Check encode.</p>
