A Merkle Sum Tree is a type of Merkle Tree that makes it efficient to verify that there is no change in the cumulative value or distribution of the leaves of a Merkle Tree.

To achieve that, a merkle Sum Tree contains numeric values at each leaf, and each node also carries the sum of the values below it. At the root of the Merkle sum tree is the sum of total values in the tree. The root of the Merkle tree contains a single hash and a numeric value.

graph TD
SUM["**Sum: 300**

Root hash: jrudj7..."] SUM --> SUM01["**Sum: 123**

Root hash: le5f5j..."] SUM --> SUM02["**Sum: 177**

Root hash: jm5doe..."] SUM01 --> BALANCE01["**Amount: 113**

Root hash: 85hlpo..."] SUM01 --> BALANCE02["**Amount: 10**

Root hash: a5z9f2..."] SUM02 --> BALANCE03["**Amount: 99**

Root hash: blf458..."] SUM02 --> BALANCE04["**Amount: 78**

Root hash: 69dfg5..."]

Root hash: jrudj7..."] SUM --> SUM01["

Root hash: le5f5j..."] SUM --> SUM02["

Root hash: jm5doe..."] SUM01 --> BALANCE01["

Root hash: 85hlpo..."] SUM01 --> BALANCE02["

Root hash: a5z9f2..."] SUM02 --> BALANCE03["

Root hash: blf458..."] SUM02 --> BALANCE04["

Root hash: 69dfg5..."]

Merkle Sum trees allow efficient verification of conservation by committing to quantities associated with leaves.