Checking the Merkle Root for Block #100000
You have to byte-swap the transaction ID's before hashing them, hash each child node, and byte-swap the final hashed hex value.

Transaction 1 (Coibase Transaction)
8c14f0db3df150123e6f3dbbf30f8b955a8249b62ac1d1ff16284aefa3d06d87

To Byteswap it you can use:

a = "8c14f0db3df150123e6f3dbbf30f8b955a8249b62ac1d1ff16284aefa3d06d87"
"".join(reversed([a[i:i+2] for i in range(0, len(a), 2)])) @Greg Hewgill

Byteswapped = 876dd0a3ef4a2816ffd1c12ab649825a958b0ff3bb3d6f3e1250f13ddbf0148c

Transaction 2
fff2525b8931402dd09222c50775608f75787bd2b87e56995a7bdd30f79702c4 
Byteswapped = c40297f730dd7b5a99567eb8d27b78758f607507c52292d02d4031895b52f2ff

You want to concatenate the byte-swapped transaction values of 1 and 2. Transaction 1 goes first.

876dd0a3ef4a2816ffd1c12ab649825a958b0ff3bb3d6f3e1250f13ddbf0148cc40297f730dd7b5a99567eb8d27b78758f607507c52292d02d4031895b52f2ff

To hash this hex string you can use the following code running Python in your command terminal:


  
    
      import hashlib
      
      transaction12_hex = "876dd0a3ef4a2816ffd1c12ab649825a958b0ff3bb3d6f3e1250f13ddbf0148cc40297f730dd7b5a99567eb8d27b78758f607507c52292d02d4031895b52f2ff"
      
      transaction12_bin = transaction12_hex.decode('hex')
      
      hash = hashlib.sha256(hashlib.sha256(transaction12_bin).digest()).digest()
      
      hash.encode('hex_codec')
      
      15b88c5107195bf09eb9da89b83d95b3d070079a3c5c5d3d17d0dcd873fbdacc
    
  


Transaction 3
6359f0868171b1d194cbee1af2f16ea598ae8fad666d9b012c8ed2b79a236ec4
Byteswapped = c46e239ab7d28e2c019b6d66ad8fae98a56ef1f21aeecb94d1b1718186f05963

Transaction 4
e9a66845e05d5abc0ad04ec80f774a7e585c6e8db975962d069a522137b80c1d
Byteswapped = 1d0cb83721529a062d9675b98d6e5c587e4a770fc84ed00abc5a5de04568a6e9

If you do the same thing for transaction 3 and 4 the final hash is: 49aef42d78e3e9999c9e6ec9e1dddd6cb880bf3b076a03be1318ca789089308e

Our last step is to combine the final hashed value of 1 &amp; 2 and 3 &amp; 4 and double hash it and byte-swap it.

Our answer is f3e94742aca4b5ef85488dc37c06c3282295ffec960994b2c0d5ac2a25a95766 the Merkle Root.